| 摘要 |
An aqueous coating composition comprises at least 76 per cent of polyvinyl alcohol, from 0.02 to 12 per cent of a dichromate and from 0.4 to 12 per cent phenol, calculated on the dry weight of the materials. Specified dichromates are ammonium and alkali-metal dichromates. When the percentage of dichromate is two or more the material is light-sensitized, while with a percentage below 2 moulding of the dispersion is prevented and further addition of dichromate makes the material light-sensitive. The coating composition may be applied to a metal baseplate to form a lithographic printing-plate.
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